How to package my own CYCLES fork as an add-on for blender (as a .zip file)
Not easily, the way Cycles is integrated requires access to Blender APIs that are not available to addons. In principle it is possible to do all the same things through the Python API, but that would require rewriting a lot of the Blender to Cycles conversion code. 

I got this answer here https://devtalk.blender.org/t/how-to-package-my-own-cycles-fork-as-an-add-on-for-blender-as-a-zip-file/1765